package lq;

import java.util.Scanner;

public class lq2002 {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        double r,v;
        while (sc.hasNext()){
            r=sc.nextDouble();
            v=3.1415927*r*r*r*4.0/3.0;
            System.out.printf("%.3f",v).println();
        }
    }
}
